This invention relates generally to the field of distance measuring systems, and more specifically to the field of measuring systems with audible annoucement of distance to a desired object or target and to such systems which require little operator intervention.
There are many applications for distance measuring equipment. For example, at the current state-of-the-art there is no safe way for a driver to back up a large vehicle and observe a human or any obstructing object located in the "blind spot" inherent to all vehicles and particularly troublesome to trucks. A closed circuit television system has been used; however, this system requires that the driver divert his attention to observe a television screen and, therefore, presents a safety hazard. Additionally, the prohibitive cost of a CCTV system makes it avaialable to a limited number of truck owners.
Another application is a system with audible output designed as a sensory aid for use by a sightless person.
A number of inventions have already been provided in the field of audible output distance measuring systems. F. Welland (U.S. Pat. No. 4,234,941) provides a verbal readout depth sounding system, and E. Bickley, Jr. et al (U.S. Pat. No. 4,135,188) provides a method and apparatus for orally announcing vehicle speed; however, both inventions are unsuitable for the intended purpose of this invention. The Welland invention is designed primiarly to measure depth in a fluid medium and the Bickley invention measures velocity whereas the instant invention measures distance. Importantly, both Bickley and Welland use a scheme for selecting the words to be synthesized in which the outputs from the measuring device are separated into a tens digit and a units digit and then each is synthesized, thereby producing a generalized two-digit number so that 25 would be vocalized as "two five".
L. Russell (U.S. Pat. No. 3,321,737) provides sonartype sensory aids which measure distance but provides 5 output tones and not synthesized speech at all. M. Rodriquez (U.S. Pat. No. 4,439,8640) provides a sonar rangefinder system whose output controls, typically, servo type camera setting functions but no audible verbal readings. Finally, W. Westfail, Jr. (U.S. Pat. No. 3,942,149) provides a solid state depth finder which provides a visual readout of depth in a fluid medium.